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Difficulty: MediumGeneral Internal Medicine

A 68-year-old man is evaluated in the hospital for worsening shortness of breath. He was admitted 3 days ago for community-acquired pneumonia. A sputum culture obtained on admission grew *Streptococcus pneumoniae* sensitive to amoxicillin, and he has been receiving targeted oral amoxicillin therapy. Over the past 12 hours, he has become progressively dyspneic and developed swelling in his legs. Medical history is significant for hypertension, type 2 diabetes mellitus, and a 40-pack-year smoking history. The patient is alert and anxious. Temperature is 37.1°C (98.8°F), blood pressure is 156/92 mm Hg, pulse is 105/min, and respirations are 24/min. Pulse oximetry shows 89% on room air. Physical examination reveals elevated jugular venous pressure. Lung auscultation reveals prolonged expiration, scattered wheezes bilaterally, and bibasilar crackles. Cardiac examination shows regular tachycardia with a third heart sound (S3). There is 2+ bilateral pitting edema to the mid-calves.

Laboratory studies show:
- Sodium: 138 mEq/L
- Potassium: 4.2 mEq/L
- Chloride: 104 mEq/L
- Bicarbonate: 14 mEq/L
- Blood urea nitrogen: 30 mg/dL
- Serum creatinine: 1.5 mg/dL
- Lactic acid: 4.5 mmol/L (Normal: 0.5-1.0)
- Thyroid-stimulating hormone (TSH): 0.1 mU/L (Normal: 0.4-4.0)
- Free T4: 0.5 ng/dL (Normal: 0.9-2.4)

Arterial blood gas analysis on room air:
- pH: 7.28
- PaCO2: 30 mm Hg
- PaO2: 62 mm Hg

Which of the following is the most appropriate next step in the management of this patient?

  1. Intravenous furosemideAnswer
  2. B
    Inhaled albuterol and oral prednisone
  3. C
    Intravenous piperacillin-tazobactam
  4. D
    Oral levothyroxine
  5. E
    Endotracheal intubation

Answer

The correct management is the administration of intravenous furosemide to treat acute decompensated heart failure.
The correct next step in management is intravenous furosemide. The patient's presentation of progressive dyspnea, elevated jugular venous pressure, an S3 gallop, bibasilar crackles, and lower extremity edema is highly diagnostic of acute decompensated heart failure (ADHF). His recent severe infection likely acted as a physiologic stressor that precipitated this cardiovascular exacerbation. The immediate treatment for ADHF with volume overload focuses on rapid diuresis using intravenous loop diuretics, such as furosemide, which reduce preload and relieve pulmonary congestion.

Step-by-Step Solution

1
Analyze the patient's physical examination findings and clinical history.
The patient exhibits elevated jugular venous pressure, an S3 gallop, bibasilar crackles, and pitting edema in the context of a recent systemic stressor (pneumonia).
These physical findings are classic for fluid overload and accurately differentiate acute decompensated heart failure from a primary pulmonary exacerbation.
2
Evaluate the arterial blood gas to assess acid-base status and rule out impending respiratory failure.
Using Winter's formula (PaCO2=1.5×[HCO3−]+8PaCO_2 = 1.5 \times [HCO_3^-] + 8), the expected PaCO2PaCO_2 is 1.5×14+8=29±21.5 \times 14 + 8 = 29 \pm 2 mm Hg. The patient's actual PaCO2PaCO_2 is 3030 mm Hg.
This confirms adequate respiratory compensation for the underlying anion gap metabolic acidosis (lactic acidosis), meaning endotracheal intubation for hypercapnic respiratory failure is not indicated.
3
Determine the most appropriate initial pharmacological therapy.
Intravenous furosemide is selected as the next best step.
Intravenous loop diuretics rapidly reduce volume overload and improve pulmonary congestion in patients presenting with acute decompensated heart failure.

Key Concept

The diagnosis of acute decompensated heart failure requires identifying signs of fluid overload (S3 gallop, JVD) to differentiate it from COPD exacerbations, and necessitates immediate diuresis rather than antibiotics or intubation for appropriately compensated acid-base states.
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Topics

General Internal Medicine

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